Cylinder and piston arrangement



April 11, 1967 H. BIER] I 3,313,215

CYLINDER AIQID PISTON ARRANGEMENT Filed Oct. 18, 1965 2 Sheets-Sheet 1 KNVENTOR H nus Bu'ER BY (D Q KQUMM H. BIERI CYLINDER AND PISTON ARRANGEMENT April 11, 1967 2 Sheets-Sheet 2 Filed Oct. 18, 1965 Unite grates Patent" 3,313,215 Patented Apr. 11, 1967 3,313,215 CYLINDER AND PISTON ARRANGED KENT Hans Bieri, Uster, Switzerland (Obereck, Pfafiikon, Zurich, Switzerland) Filed Oct. 18, 1965, Ser. No. 497,428 Claims priority, appiication Switzerland, Feb. 9, 1962, 1,606/62 5 Claims. (Cl. 92S6) This application is a continuation-impart of my copending, United States application, Ser. No. 256,017, filed February 4, 1963 and entitled, Cutter For Separating 21 Strand of Material, now patent No. 3,224,310.

The present invention has reference to an improved cylinder and piston arrangement, particularly for large hydraulic machinery, and especially suitable for use in conjunction with operable elements, where due to the nature of the operation, the piston should not rotate relative to the cylinder.

Such type applications occur, for instance, during the cutting of metal stock, such as bars or rods which may be i in transit during the time of cutting. Whether the metal rod or bar is moving or not, in any case a cutter means which may have one cutter-knife or cutter element attached to the piston rod or ram of the piston slidably arranged in the cylinder should not rotate relative to the cylinder, otherwise such cutter element will not be properly positioned with respect to its cooperating cutter element.

Now, the prior art has already proposed a number of solutions for preventing rotation of a piston within its cylinder. According to one known construction the means for preventing rotation of the piston are located externally of the cylinder housing and thus require a relatively massive support and separate provision for lubricating such rotation-preventing means. Not only does such physical structure increase the cost of manufacture for this type piston and cylinder arrangement, but furthermore, it is quite complicated in operation, requiring considerable maintenance to keep it properly functioning.

Now a primary object of my invention is to providean improved working cylinder and working piston arrangement wherein there is provided means for preventing rotation of the piston which as least partially extends into the compartment of the cylinder and is lubricated by the same working mediumused to drive the piston, to thereby effectively protect such rotation-preventing "means and render same free from soiling and maintenance.

A further, important object of this invention has reference to an improved working cylinder and working piston arrangement wherein the piston and piston rod are prevented frorn rotating relative to the longitudinal axis of the cylinder, the arrangement effected such that the pressurized working medium used to reciprocate the piston can also be employed for lubricating the structure which prevents rotation of such piston.

Still another noteworthy object of this invention is to provide a cylinder and piston arrangement wherein the piston rod connected with the piston is guided at spaced locations axially thereof, so that it is possible to refrain from using the outer surfaces of the piston for guiding thereoflwhereby the piston itself operates with play with regard to the walls of the cylinder compartment.

Yet a further important object of this invention is to provide an improved working cylinder and working piston arrangement where the sealing members for the piston rod are not subjected to the high pressure of the working liuid medium used to reciprocate the piston, rather to the lower pressure of leakage working medium collected at reduced pressure in a collecting chamber disposed externally of the chamber in which the pressurized working fiuid medium acts upon the piston, so that it is possible to increase the life of these piston rod-sealing members, to have less friction losses and, in :fact, less leakage losses towards the outside of the cylinder.

In order to implement these and still further objects of my invention, which will become more readily apparent as the description proceeds, the new and improved cylinder and piston arrangement of my invention comprises cylinder means incorporating a cylinder housing internally providing a cylinder compartment, with at least one piston including a piston rod slidably disposed for recipro cation within said cylinder compartment. Means are provided for the cylinder means for admitting a working medium under pressure into said cylinder compartment in order to reciprocate the aforesaid piston. Additionally, and according to an important aspect of this invention, there is further provided means for preventing rotation of the piston relative to the cylinder means, said rotationpreventing means extending at least partially into the cylinder compartment and being lubricated by the working medium.

My invention also contemplates providing an improved guiding action for the piston rod in that, at least one and preferably two guide sleeves which are spaced from one another are arranged in the cylinder housing and slidably guide the piston rod carrying the piston along a fixed guide path. By virtue of this feature it is possible to construct the piston to have play with respect to the walls of the cylinder compartment, so that no effective guiding action prevails between the piston and cylinder walls, guiding of such piston being primarily provided at such guide sleeve or sleeves. Moreover, the at least one guide sleeve divides the cylinder compartment into two chambers, one of which provides a piston chamber for the piston and the other a collecting chamber for working medium which has leaked past such guide sleeve and out of the one chamber containing the piston. Advantageously, this guide sleeve provides a throttle means for re-' ducing the pressure of the leaked working medium considerably below that prevailing at'the time such working medium is used to drive the piston within the piston chamber, so that the sealing rings for the piston rod are only subjected to the considerably lower pressure of the leaked working medium, thereby ensuring for increased life of these sealing rings, less friction losses, and less loss of leakage medium towards the outside. There are still further important features of my invention, yet such will be explained in considerable detail hereinafter.

Thus, other features, objects and advantages of the invention will become apparent by reference to the following detailed description and drawings wherein like reference characters have been used for substantially the same or analogous elements throughout the various embodiments, and in which:

FIGURE 1 is a vertical sectional view through a first embodiment of cylinder and piston arrangement designed according to the teachings of the present invention;

FIGURE 2 is a sectional view of the cylinder and piston arrangement of FIGURE 1, taken along line 11-11 thereof;

FIGURE 3 is a vertical sectional view of a second em bodiment of inventive cylinder and piston arrangement;

FIGURE 4 is a cross-sectional view of the piston and cylinder arrangement of FIGURE 3, taken along line IVIV thereof;

FIGURE 5 is a vertical sectional view of a third embodiment of inventive cylinder and piston arrangement;

FIGURE 6 is a cross-sectional view of the cylinder and piston arrangement of FIGURE 5, taken along line VIVI thereof;

FIGURE 7 is a vertical sectional view, similar to the previous figures, showing a variant form of cylinder and piston arrangement according to the present invention employing two piston members; and

FIGURE 8 is a cross-sectional view of the cylinder and piston arrangement of FIGURE 7, taken along line VIlI--Vlli thereof.

Describing now the drawings, and initially turning attcntion to the embodiment of cylinder and piston arrangement depicted in FIGURES 1 and 2, it will be recognized that the cylinder arrangement or means 10 comprises an open-ended cylinder housing 11assumed here to be vertically arranged, but obviously could assume other positions-and which is closed at one end by a d0me-shaped upper cover member 12 and at the opposite end by a lower cover member 13. The cylinder housing 11 is hollow so as to provide therein a cylinder compartment 14 in which there is slidably arranged at least one piston 15 having a piston rod 16 to which there can be connected any suitable operable element which is to be driven.

Means are provided for preventing rotation of the piston 15 and its piston rod 16 relative to the cylinder housing 11. In this exemplary embodiment such means comprises a linear guide device composed of a keyway arrangement having a key 17 affixed to a slot 18 provided at the piston rod 16 and slidable in a straight slot or keyway 19 formed at an upper guide sleeve or bushing 20. It will be noticed that this guide sleeve or bushing 20 is arranged internally of the cylinder compartment 14, bears against inwardly directed shoulders 21 provided at the cylinder housing 11 and serves to divide the cylinder compartment 14 into two chambers 22 and 23. The chamber 22 provides the piston chamber in which the piston 15 is reciprocated, whereas the other chamber 23 provides a collecting chamber for receiving and collecting any working medium used to reciprocate such piston 15 which may leak past the guide sleeve 20.

Now in order to be able to admit a working medium under pressure to opposite faces of the piston member 15 so as to reciprocate the latter in a controlled manner, the dome-shaped upper cover member 12 is provided with a central aperture or bore 24 which communicates a nonillustrated supply-source, of any desired construction and known to the art, containing a working medium under pressure with the upper face 15a of the working piston 15, whereas a further aperture or bore 25 provided at the side wall of the cylinder housing 11 communicates the means for supplying pressurized working medium with the lower face 15b of the piston 15. It should thus be apparent that by selectively admitting in alternation pressurized working medium via the bores 24 and 25 it is possible to reciprocate in controlled manner the piston member 15 within the piston chamber 22. It will also be noticed that piston member 15 is provided with a recessed portion or slot 150 at its central region in which there is inserted a piston sealing ring 26 which here encircles the entire piston 15. The external diameter of the piston 15 is advantageously smaller than the diameter of the walls 27 bounding the piston chamber 22 for the piston 15, so that the latter slides with play within such chamber 22. In other words, the surfaces of the piston 15 do not contact the walls 27 of the piston chamber 22 to guide the piston therein.

In the first instance such guiding action is provided by the guide sleeve or bushing 20 having a central bore 28 through which the piston rod 16 piercingly extends. This guide sleeve or bushing 20 also has the important function of providing a throttle means for throttling working medium which is under relatively high pressure in the piston chamber 22 and which seeps past the piston rod 16 and through the central bore 28 into the collecting chamber 23, to thereby considerably reduce such pressure, typically to the static pressure prevailing in the nonillustrated leakage working medium return lines communicating with a bore 29 at the cylinder housing 11 and leading to the collecting chamber 23, so that the leakage working medium, for instance oil, can be returned to a suitable reservoir or supply source (not shown). It should thus be appreciated that in this embodiment, the means for preventing rotation of the piston 15 and piston rod 16 relative to the cylinder means 10, namely the key 17 and keyway 19 are lubricated by the same pressurized working medium used to drive the piston 15, each time such pressurized medium is admitted through bore 25 to drive piston 15 towards the dome-shaped cover member 12. Hence, no separate lubricating arrangement is necessary for the lubrication of the piston rotation-preventing means and since it is within the cylinder housing 11 it is completely protected from dirt.

In this exemplary illustrated embodiment, there is also provided axially of the piston rod 16, and in spaced relation with respect to the guide sleeve or bushing 20, a further guide sleeve or bushing 30 which is located re mote from the piston chamber 22 and here bounds the collecting chamber 23. This guide sleeve or bushing 30 provides a further guide location for the piston rod 16, and it will be seen that a fixed guide path which extends at least over the length L is provided for the piston rod 16 by virtue of these two spaced guide sleeves or bushings 20 and 30. Of course, the lower cover member 13 also provides a guiding action at the piston rod 16. This lower cover member 13 presses the guide sleeve 30 provided with a central bore 31 through which piercingly extends the piston rod 16, against the shoulders 32 of the cylinderhousing 11. This cover member 13 is also provided with a central bore 33 through which extends the piston rod 16 towards the outside of the cylinder 10. Furthermore, the cover member 13 is provided with sealing rings 34 and 35, the sealing ring 34 cooperating with theslidable piston rod 16, whereas the sealing ring 35 cooperates with the inner walls of the cylinder housing 11.

It will be recalled that is was previously mentioned that the pressure of the leakage or leaked working medium collected in the collecting chamber 23 is considerably below the pressure prevailing at such working medium when disposed in the piston chamber 22 in which the piston 15' is driven. By virtue of the fact that the working medium located in collecting chamber 23 is at a reduced pressure, the sealing rings will only be subjected to the low pressure working medium which may seep along the piston rod 16 and the bores 31 and 33 of the sleeve 30 and cover 13, respectively, so that the service life of these sealing rings, particularly ring 34, is considerably increased, there is less friction losses, and less leakageof working medium contained in chamber 23 towards the outside of the cylinder. Finally, it is mentioned that the cover member 12 is also provided with sealing ring means 36 which engage with the upper end of the inner walls 27 of the cylinder housing 11.

In the variant embodiment of cylinder and piston arrangement depicted in FIGURES 3 and 4, it will be immediately recognized bycomparing the two embodiments that there is a certain basic similarity between the two constructions, so that like reference characters have again been conveniently-employed for the same or analogous elements, and now only the differences between the two embodiments will be considered in detail. In this embodiment, the means for preventing rotation of the piston 15 and piston rod 16 are not provided at the guide sleeve 20, rather are arranged at the cylinder housing 11 and the piston 15. Specifically, by referring to FIGURE 3 it will be noted that the piston 15 is provided with an axially extending keyway 37 in the form of a slot into which engages a stepped key member 33. The latter is aflixed to the walls of the cylinder housing 11 and extends through a bore 39 provided at such walls into engagement with the keyway slot 37. In all other respects the embodiment depicted in FIGURES 3 and 4 is similar to that described in connection with FIGURES 1 and 2.

The embodiment of cylinder and piston arrangement depicted in FIGURES 5 and 6 is also quite similar to the embodiments previously disclosed, for which reasons the same reference characters have again been used for similar elements. In this embodiment there is basically a reversal of the arrangement of key and keyway of FiG- URES 3 and 4, since here the inner wall 27 of the cylinder housing 11 is provided with a lengthwise extending keyway slot 40 and the piston carries the key 41 which slides within the keyway slot 46. With respect to the arrangements disclosed in the embodiments of FIGS. 3 and 5, the key and keyway arrangement of FIGURE 3 is somewhat preferred because, it must be remembered that since these cylinders are typically designed for large hydraulic machines the inner walls 27 cannot be readily hardened and ground, whereas it would be easier to grind and harden the surface of the piston 15, so that it would be preferable to have the keyway slot arranged at such hardened and ground piston 15. Once again, it is mentioned by way of completeness that the remaining physical structure and operation of this last-considered embodiment is similar to the previous embodiments.

The remaining embodiment depicted in FIGURES 7 and 8 differs from those previously disclosed, in the first instance in that here there i provided a further piston member 42 slidably arranged in the lower chamber or compartment 43 formed by the guide sleeve or bushing which separates lower compartment 43 from the up per compartment or chamber 22 in which the piston 15 is slidably arranged. This guide sleeve 20 again provides a guiding action at the piston rod 16 and also is provided with sealing rings 59. It will also be seen that the piston rod 16 is provided with an axially extending central bore 44 which communicates with radially extending ducts 45. Thus working medium under pressure coming from the bore 24 at the dome-shaped cover member 12 not only acts against the upper face 15a of the piston 15 but can also move through the central bore 44 and radial ducts 45 to act against the upper face 42a of the piston 42, to thu further assist in moving the piston rod 16 downwards in the cylinder housing 11.

In this embodiment it is to be understood that the piston 42 also provides a throttle path for any working medium under high pressure which seeps past the piston ring 46 thereof from the upper chamber region of the chamber 43 above piston face 42a into the lower chamber portion or region 47, the latter corresponding in function to the col-lecting chamber 23 for leakage oil of the previous embodiments. Here, however, due to the fact that a further piston 42 is movable within the chamber 43 of the cylinder housing 11, this collecting chamber 47 is an expansible one, ie its volume changes depending upon the movement of the throttling piston member 42. Thus, any leakage working medium contained in the collecting chamber portion 47 is at considerably lower pres sure than the pressure prevailing in the upper portion of chamber 43 and also in the chamber 22. It will also be noted that in this embodiment the means for preventing rotation of the piston rod 16 and the piston 15 and 42 relative to the cylinder housing 11 comprise a key 48 carried by the piston rod 16 which cooperates with a keyway 49 provided at the lower closure member 13. .Here, this lower cover or closure member 13 also serves to guide the piston rod 16 together with the guide sleeve 20 spaced axially therefrom, and in this embodiment the second guide sleeve or bushing has been omitted, since here the cover member 13 completely takes over its function to provide together with the sleeve 20 a fixed guide path for the path for the piston rod 16, as designated by refence character L. It should also be appreciated that the key 48 and keyway 49 are lubricated by the collected leaked or leakage working medium appearing in the collecting chamber 47 and the sealing rings 34, are only exposed to the low pressure of the thus collected medium.

Finally, it is mentioned that while in the embodiment of FIGURE 1 the key and keyway arrangement are lubricated during such time as a pressurized working medium is admitted through bore 25 for the upstroke of the piston 15, in the embodiments of FIGURES 3 and 5 the key and keyway are lubricated during both the -upand downstroke of the piston member 15. However, in each of the embodiments disclosed herein the same working medium which is used to drive the working piston 15 is also employed for lubricating the means which prevent rotational movement of said piston within its cylinder housing 11. Also, by way of completeness it is pointed out that in those instances where the key and keyway are arranged at the piston 15, the piston sealing ring 26 would, of course, be interrupted at the point of provision of such key and keyway, such also being the case for the sealing ring 34 (FIGURE 7).

Thus, not only'have I provided a new and improved arrangement for guiding a piston and piston rod within its cylinder, but I have also etfectively prevented rotation of the piston relative to the cylinder by means which at least partially extend into the compartment of the cylinder and are lubricated by the working medium. Furthermore, in each of the embodiments disclosed I have provided a collecting chamber and a throttle means so that the pressure of the working medium moving into the collecting chamber is considerably reduced, whereby at least the packing seals for the piston rod are subjected only to a relatively low pressure leakage working medium, so that their longevity and service is considerably enhanced, the friction losses are reduced, and there is less leakage loss towards the outside of the cylinder. These are only some of the more important advantages which are gained by virtue of the teachings of my invention.

While there is shown and described present preferred embodiments of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practised within the scope of the following claims.

What is claimed is:

1. A cylinder and piston arrangement comprising a housing having a chamber formed therein; a guide sleeve having a bore therethrough dividing said housing chamber into a cylinder compartment and a working fluid collecting chamber; closure means at the opposite ends of said housing chamber closing said cylinder compartment and said collecting chamber; at least one piston means including a piston slidably disposed in said cylinder compartment and a piston rod slidable in said bore; the relative sizes of said piston rod and bore being such as to provide for the restricted leakage of fluid around said piston rod and into said collecting chamber to thereby considerably reduce the pressure of said leaked working fluid in said collecting chamber; means for admitting a working fluid under pressure into said cylinder compartment for reciprocatmg said piston and said piston rod; rotation preventing means located at least partially in said housing chamber and comprising a cooperating key and keyway means, one of said key and keyway means being fixed relative to the housing chamber, the other of said key and keyway means being located on the exterior peripheral surface of said piston means whereby said rotation preventing means is lubricated by said working fluid.

2. A cylinder and piston arrangement as defined in claim 1, including an additional guide sleeve supported within said housing and spaced axially from said first mentioned guide sleeve, said second mentioned guide sleeve having a bore therethrough, through which said piston rod extends.

3. A cylinder and piston arrangement as defined in claim 2 wherein the closure means at the end of the housing chamber having the collecting chamber is provided with a sealing ring whereby said sealing ring will be subjected to a reduced pressure in said collecting chamber.

4. A cylinder and piston arrangement as defined in claim 1, wherein the closure means at the end of the housing chamber having the collecting chamber is provided with a sealing ring whereby said sealing ring will be subjected to the reduced pressure present in said collecting chamber.

5. A cylinder and piston arrangement as defined in claim 1 wherein said piston is provided with the keyway 20 and said key is carried by said cylinder housing and cooperates with said keyway.

References Cited by the Examiner UNITED STATES PATENTS 11/1908 Hamilton et a1 92111 X 5/1935 Vickers 9286 X 4/ 1951 Rosenberg 92-166 5/1956 Strayer 92166 X 8/1957 Place et al 9286 X 12/1957 Gold et a1 9286 X 10/1960 Malpass 92-165 X lO/l965 Knable 92151 X 5/1966 De R00 92ll0 FOREIGN PATENTS 10/ 1940 Germany.

MARTIN P. SCHWADRON, Primary Examiner.

EDGAR W. GEOGHEGAN, Examiner.

I. C. COHEN, Assistant Examiner. 

1. A CYLINDER AND PISTON ARRANGEMENT COMPRISING A HOUSING HAVING A CHAMBER FORMED THEREIN; A GUIDE SLEEVE HAVING A BORE THERETHROUGH DIVIDING SAID HOUSING CHAMBER INTO A CYLINDER COMPARTMENT AND A WORKING FLUID COLLECTING CHAMBER; CLOSURE MEANS AT THE OPPOSITE ENDS OF SAID HOUSING CHAMBER CLOSING SAID CYLINDER COMPARTMENT AND SAID COLLECTING CHAMBER; AT LEAST ONE PISTON MEANS INCLUDING A PISTON SLIDABLY DISPOSED IN SAID CYLINDER COMPARTMENT AND A PISTON ROD SLIDABLE IN SAID BORE; THE RELATIVE SIZES OF SAID PISTON ROD AND BORE BEING SUCH AS TO PROVIDE FOR THE RESTRICTED LEAKAGE OF FLUID AROUND SAID PISTON ROD AND INTO SAID COLLECTING CHAMBER TO THEREBY CONSIDERABLY REDUCE THE PRESSURE OF SAID LEAKED WORKING FLUID IN SAID COLLECTING CHAMBER; MEANS FOR ADMITTING A WORKING FLUID UNDER PRESSURE INTO SAID CYLINDER COMPARTMENT FOR RECIPROCATING SAID PISTON AND SAID PISTON ROD; ROTATION PREVENTING MEANS LOCATED AT LEAST PARTIALLY IN SAID HOUSING CHAMBER AND COMPRISING A COOPERATING KEY AND KEYWAY 